Chucking mechanism, brushless motor having the chucking mechanism, and disk driving apparatus having the brushless motor

ABSTRACT

A movement pivot receiving portion which receives a movement pivot portion of a claw member and a movement support receiving portion which receives a movement assist portion of the claw member are arranged radially within a cylindrical portion of a center case. By virtue of such configuration, both receiving portions are designed with a greater degree of freedom within a space between an inner circumferential surface of the cylindrical portion and an outer circumferential surface of a base portion. Therefore, the claw member may be designed to have a preferable thickness while achieving a preferable movement of in an axial direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chucking mechanism operable todetachably set thereon a discoid disk, and to a motor including thechucking mechanism, and a disk driving apparatus including the motor.

2. Description of Related Art

In recent years, a slot loading mechanism in which a disk is slid in andout of a disk driving apparatus is used in a personal computer(hereinafter, referred to as PC). This mechanism is particularly usefulfor a PC having a slim shape.

The slot loading mechanism requires no tray moving the disk to a spindlemotor which rotates the disk, and therefore is allowed to be slim.However, there is an increased demand to further slim down the diskdriving apparatus. In order to further slim down the disk drivingapparatus, the spindle motor used therein also needs to be slimmer. Itis, however, a difficult task to reduce a thickness of a chuckingmechanism on which the disk is removably set and which is arranged inthe spindle motor.

Also, the disk driving apparatus having applied thereon the slot loadingmechanism usually retains the disk by itself without using a clampingmember in order to achieve a thin chucking mechanism.

FIG. 14 is a diagram showing a cross sectional view, in an axialdirection, of a conventional configuration of the chucking mechanism.

According to FIG. 14, a chucking mechanism 1 includes a turn table 2having a disk setting surface 2 a on which a disk (not shown in FIG. 14)having a central opening portion, a center case 3, a plurality of clawmembers 4, and an elastic member 5 providing a radial force for eachclaw member 4. The center case 3 includes a cylindrical portion 3 aaround which an inner circumferential surface of the central openingportion of the disk will be arranged, a top plate portion 3 b arrangedsuch as to cover a top end of the cylindrical portion 3 a, and aplurality of openings 3 c allowing the claw members 4 to movetherethrough. The claw member 4 includes a disk retaining surface 4 awhich makes contact with the central opening portion so as to retain thedisk. Also, the center case 3 preferably includes an upward guidingsurface 3 d which makes contact with the claw member 4 so as to guide asliding movement of the claw member 4.

SUMMARY OF THE INVENTION

A chucking mechanism according to the present invention, a claw memberincludes a movement pivot portion and a movement support portion at aportion of the claw member radially further inward than the movementpivot portion in order to allow the claw member to move in a radial andan axial direction. When the movement support portion makes contact withthe movement support receiving portion, the radial movement of the clawmember is well supported, and therefore, a disk will be retained by thechucking mechanism effectively.

Other features, elements, steps, characteristics and advantages of thepresent invention will become more apparent from the following detaileddescription of preferred embodiments thereof with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view in an axial direction showinga brushless motor according to a preferred embodiment of the presentinvention.

FIG. 2 is a plan view of a chucking mechanism of the present inventionas seen from above.

FIG. 3 a is a schematic cross sectional view of a center case of thepresent invention.

FIG. 3 b is a plan view of the center case as seen from above.

FIG. 4 a is a side view of a claw member of the present invention.

FIG. 4 b is a front view of the claw member of the present invention.

FIG. 4 c is a plan view of the claw member of the present invention.

FIG. 4 d is a schematic cross sectional view of the claw member of thepresent invention.

FIG. 5 is a cross sectional view of the chucking mechanism before a diskmakes contact therewith.

FIG. 6 is a cross sectional view of the chucking mechanism when the diskbegins to make contact with a disk guiding surface.

FIG. 7 is a cross sectional view of the chucking mechanism according tothe present invention in which a movement support portion is arranged ata position of a curved surface.

FIG. 8 is a cross sectional view of the chucking mechanism according tothe present invention in which the movement support portion slides overan upper movement support surface.

FIG. 9 is a schematic cross sectional view of the chucking mechanismaccording to the present invention in which a tip portion thereof is atan axially lowest position.

FIG. 10 is a schematic cross sectional view of the chucking mechanismaccording to the present invention in which the claw member retains thedisk.

FIG. 11 is a cross sectional view of the chucking mechanism according tothe present invention in which an inner configuration of the clawportion according to FIG. 9 is shown.

FIG. 12 is a graph indicating a correlation between a rate of occurrenceof chucking failure and an axial height of a tip portion of the clawmember of the chucking mechanism according to the present invention.

FIG. 13 is a cross sectional view of a disk driving apparatus accordingto a preferred embodiment of the present invention.

FIG. 14 is a cross sectional view of a conventional chucking mechanismbefore a disk makes contact therewith.

FIG. 15 is a cross sectional view of the conventional chucking mechanismwhen the disk begins to make contact with a claw member.

FIG. 16 is a cross sectional view of the conventional chucking mechanismin which a tip portion thereof is at an axially lowest position.

FIG. 17 is a cross sectional view showing a relationship between theclaw portion and the elastic member.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Note that in the description of the preferred embodiments of the presentinvention herein, words such as upper, lower, left, right, upward,downward, top, and bottom for describing positional relationshipsbetween respective member and directions merely indicate positionalrelationships and directions in the drawings. Such words do not indicatepositional relationships and directions of the member set in an actualdevice. Also note that a direction parallel to Z axis herein will bereferred to as an axial direction. Also, note that the referencenumerals, figure numbers and supplementary descriptions are shown belowfor assisting the reader in finding corresponding components in thedescription of the preferred embodiments below to facilitate theunderstanding of the present invention. It should be noted that theseexpressions in no way restrict the scope of the present invention.

Structure of Brushless Motor

Hereinafter a brushless motor according to a preferred embodiment of thepresent invention will be described with reference to FIG. 1. FIG. 1 isa schematic cross sectional view in an axial direction of a brushlessmotor according to a preferred embodiment of the present invention.

Hereinafter, a stator portion of the brushless motor will be described.

A housing 10 preferably having a substantially cylindrical shapeconcentric with a central axis J1 is preferably made by a deformationprocess such as cutting performed on a copper base material. A sleeve 20is affixed to an inner circumferential surface of a cylindrical portion11 of the housing 10. The sleeve 20 preferably having a substantiallycylindrical shape is a sintered member impregnated with oil.

The housing 10 preferably includes at a portion axially below thecylindrical portion 11 a stator base portion 12 preferably having asubstantially cylindrical shape extending radially outward, wherein thecylindrical portion 11 and the stator base portion 12 are preferablyformed integrally. The stator base portion 12 preferably includes at abottom surface thereof a protrusion extending radially inward and aprotrusion extending radially outward (hereinafter, referred to as innercircumferential protrusion 12 a and outer circumferential protrusion 12b, respectively). A plate 30 is arranged extending inwardly from theinner circumferential protrusion 12 a. The plate 30 and the innercircumferential protrusion 12 a are affixed to one another by calking. Athrust plate 40 preferably having a substantially disk shape preferablymade of a material excellent in abrasion resistance quality is arrangedaxially above the plate 30.

The housing 10 preferably includes at an outer circumferential portionof the stator base portion 12 a stator setting portion 12 c for settingthereon a stator 50 (described below). The stator 50 preferably includesa stator core 51 having a core back portion 51 a, a plurality of toothportions 51 b each extending radially outward of the core back portion51 a, and a plurality of coils 52 each formed by winding a plurality oftimes a conductive wire around each tooth portion 51 b.

The housing 10 preferably includes at a portion radially inward of thestator 50 of the stator base portion 12 a pressuring magnet 60preferably having a substantially annular shape. The pressuring magnet60 is arranged such as to axially oppose a bottom surface of a lidportion 101 of a rotor holder 100 (described below).

An attachment board 70 is affixed by calking to the housing 10 at anouter circumferential surface of the outer circumferential protrusion 12b. A circuit board 80 for controlling a rotation of the brushless motoris arranged on a top surface of the attachment board 70. An axiallylower portion of the stator 50 is preferably covered by the circuitboard 80 and the attachment board 70.

Hereinafter, a rotor portion of the brushless motor will be described.

A shaft 90 is inserted in an inner circumferential surface of the sleeve20 in a concentric manner with the central axis J1. The shaft 90 isrotatably supported in a radial direction by the inner circumferentialsurface of the sleeve 20 while the same is supported in the axialdirection by the thrust plate 40.

A rotor holder 100 preferably having an operculated and substantiallycylindrical shape is affixed at an upper portion of the shaft 90 so asto cover the stator 50. The rotor holder 100 is preferably formed bypressing a magnetic steel plate. Also, the rotor holder 100 preferablyincludes the lid portion 101 and a cylindrical portion 102. The lidportion 101 preferably includes at a portion axially corresponding tothe sleeve 20 and the cylindrical portion 11 a leveled portion 101 a. Byvirtue of such configuration, the sleeve 20 can be extended in the axialdirection. At a bottom surface of the leveled portion 101 a a stoppermember 120 for preventing the rotor holder 100 from being removed in theaxial direction is arranged.

A rotor magnet 110 is arranged at an inner circumferential surface ofthe cylindrical portion 102. An inner circumferential surface of therotor magnet 110 is opposed, via a gap in the radial direction, to anouter circumferential surface of the tooth portions 51 b of the stator50.

A center case 210 of a chucking mechanism 200 for detachably settingthereon a disk (not shown in FIG. 1) is arranged on a top surface of thelid portion 101. A disk setting portion 101 b for setting thereon thedisk is arranged at an outer end of the lid portion 101. According tothe present preferred embodiment of the present invention the rotorholder 100 functions as a turn table.

Chucking Mechanism

Hereinafter, the chucking mechanism 200 according to a preferredembodiment of the present invention will be described with reference toFIGS. 2 through 5. FIG. 2 is a plan view of the chucking mechanism 200according to the present preferred embodiment of the present invention.FIG. 3 a is a schematic cross sectional view in the axial direction ofthe center case 210 according to the present preferred embodiment of thepresent invention. FIG. 3 b is a plan view of the center case 210according to the present preferred embodiment of the present invention.FIG. 4 a is a schematic side view of a claw member 220 according to apreferred embodiment of the present invention. FIG. 4 b is a schematicfront view of the claw member 220 according to the present preferredembodiment of the present invention. FIG. 4 c is a plan view of the clawmember 220 according to the preferred embodiment of the presentinvention. FIG. 5 is an enlarged schematic cross sectional view of thechucking mechanism 200 according to a preferred embodiment of thepresent invention.

According to FIG. 2 r the chucking mechanism 200 preferably includes thecenter case 210 preferably having a substantially cylindrical shapeconcentric with the central axis J1, and the rotor holder 100 (i.e.,turn table) having the disk setting portion 101 b. The disk settingportion 101 b set on the rotor holder 100 is preferably made of amaterial excellent in coefficient of friction.

The center case 210 preferably includes at an outer circumferencethereof a plurality of aligning claws 211 for aligning a central openingportion of the disk with the central axis J1, a plurality of clawmembers 220 arranged so as to contact with the inner circumferentialsurface of the central opening of the disk. To be more specific,according to the preferred embodiment of the present invention, thechucking mechanism 200 preferably includes three aligning claws 211 andclaw members 220 each are alternately arranged in the circumferentialdirection evenly apart from one another. Also, the center case 210preferably includes an elastic member 230 which provides radial forcefor each claw member 220.

According to FIGS. 3 a and 3 b, the center case 210 preferably includesa cylindrical portion 212, a guiding portion 213 arranged axially abovethe cylindrical portion 212 for guiding the disk to the cylindricalportion 212, a base portion 214 for connecting the center case 210 withthe rotor holder 100, and a top plate portion 215 connecting the guidingportion 213 and the base portion 214. Also, the center case 210preferably includes at a portion between the cylindrical portion 212 andan outer edge of the top plate portion 215 an opening 216 for each clawmember 220. Note that the center case 210 is made by an injectionmolding and made of a resin material and as a single component.

The opening 216 preferably includes a side opening portion 216 a openingtoward the cylindrical portion 212 and the guiding portion 213, and anupper side opening portion 216 b opening continuously upwardly from theside opening portion 216 a. It is to be appreciated that acircumferential width of the side opening portion 216 a is greater thanthat of a claw portion 221 (described later) of the claw member 220, andis smaller than that of the claw member 220 including a pair of movementsupport portions 222 (described later). Also, the side opening portion216 a penetrates to a bottom surface of the cylindrical portion 212.Also, a circumferential width of the upper side opening portion 216 b isgreater than that of the claw portion 221, and is smaller than that ofthe claw member 220 including a pair of movement pivot portions 222 a(described later) of the movement support portions 222. Also the upperside opening portion 216 b includes a widened portion 216 b 1 whosecircumferential width is equal to or greater than that of a pair ofmovement pivot receiving portions 217 (described later)circumferentially binding the claw portion 221. Also, thecircumferential width of the widened portion 216 b 1 is smaller thanthat of a pair of upper side contact surfaces 222 a 2 (described later)of the movement support portion 222. Also, the radial width of thewidened portion 216 b 1 is equal to or greater than that of movementpivot receiving portion 217.

The top plate portion 215 preferably includes at a positioncorresponding to both sides in the circumferential ends of the widenedportion 216 b 1 a lower side receiving surface 215 a which restricts aradial movement of the claw member 220 by making contact with the upperside contact surface 222 a 2.

The cylindrical portion 212 preferably includes at both sides in thecircumferential direction of the side opening portion 216 a the movementpivot receiving portion 217 which preferably includes a plane surfaceextending substantially perpendicularly to the central axis J1, andmakes contact with the movement pivot portion 222 a. The movement pivotreceiving portion 217 extends further radially inwardly than a radialposition of the movement pivot portion 222 a when the claw member 220 isat a radially innermost position. Also, the movement pivot receivingportion 217 is connected to the cylindrical portion 212. Also, at aportion connecting the movement pivot receiving portion 217 and thecylindrical portion 212 a curved surface 217 a having an indent surfaceis arranged. It is to be appreciated that the forming of the widenedportion 216 b 1 allows a configuration of a mold used to form the centercase 210 to be simple. In particular, the mold used to form the centercase 210, which is a single component, includes an upper mold, whichslides, and a lower mold, which is fixed, wherein the upper mold isremoved from the lower mold in a simple manner.

The base portion 214 includes a plane surface which is perpendicular toa direction in which the elastic member 230 extends and which makescontact with the elastic member 230. The plane surface includes amovement restricting indent portion 214 a which is equal to or slightlygreater than a diameter of the elastic member 230 which is a spring. Themovement restricting indent portion 214 a restricts a movement of theelastic member 230 in the circumferential direction. By virtue of suchconfiguration, when a radial force acting toward the central axis isapplied (i.e., when the disk is placed on the chucking mechanism 200) tothe claw member 220, the force is not dispersed in the circumferentialdirection, and therefore, the chucking mechanism 200 allows the disk tobe set thereon smoothly.

Also, the base portion 214 preferably includes at a portion connectingthe movement restricting indent portion 214 a and the top plate portion215 a lower contact surface 214 b which restricts, by making contactwith the elastic member 230, an axial movement of the elastic member230. By virtue of such configuration, when the radial force actingtoward the central axis is applied to the claw member 220, the force isnot dispersed in the axial direction, and therefore, the chuckingmechanism 200 allows the disk to be set thereon smoothly.

A movement support receiving portion 218 having two surfaces each havingan inclination different from one another is formed radially inward ofthe movement pivot receiving portion 217. The movement support receivingportion 218 includes an upper movement support surface 218 a which isconnected to the top plate portion 215 and which is inclined such thatthe further radially outward a portion thereof is the axially lower theportion is, and a lower movement support surface 218 b which is arrangedradially outwardly and axially lower and which is inclined such that thefurther radially outward a portion thereof is the axially lower theportion is. A curved surface 218 c is arranged protrudingly in thesubstantially radially outward direction at a portion connecting theupper movement support surface 218 a and the lower movement supportsurface 218 b. Also, the curved surface 218 c is formed such that anangle θ2 defined by the upper movement support surface 218 a and thecentral axis J1 is greater than an angle θ1 defined by the lowermovement support surface 218 b and the central axis J1. The angle θ1 maybe designed such that the movement assist portion 222 b will berestricted from moving in the radially inward direction. By virtue ofsuch configuration, the disk guiding surface 221 a is allowed to remaininclined radially outwardly and axially downwardly while moving on tothe upper movement support surface 218 a. Also, at the upper movementsupport surface 218 a on which the claw member 220 moves in the radialdirection, an axial movement of the tip portion 221 b will be supported.Also, at the upper movement support surface 218 a, the radial movementof the claw member 220 will be supported effectively. Therefore, thedisk will be set on the chucking mechanism 200 effectively.

Also, since the movement pivot receiving portion 217 is arrangedradially inside of the cylindrical portion 212, when the movement pivotportion 222 a makes contact with an inner circumferential surface of thecylindrical portion 212, a mechanism to restrict the claw member 220from moving exceedingly in the radial direction is formed. Therefore, aseparate mechanism for restricting the radial movement of the clawmember 220 will not be necessary. Further, the radial length of themovement pivot receiving portion 217 is freely determined within adistance between the inner circumferential surface of the cylindricalportion 212 and the base portion 214 in accordance with the radialmovement of the claw member 220.

Also, the radial length of the movement support receiving portion 218 isfreely determined within the distance between the inner circumferentialsurface of the cylindrical portion 212 and the base portion 214 inaccordance with the radial movement of the claw member 220. Also, sincethe movement support receiving portion 218 and the movement pivotreceiving portion 217 are arranged such as not to overlap in the radialdirection with one another, the movement of the movement pivot receivingportion 217 will not be in the way of the movement support receivingportion 218 or vice-versa. Therefore the movement pivot receivingportion 217 and the movement support receiving portion 218 each will bedesigned in accordance with their movement.

Also, the lower side receiving surface 215 a is arranged between themovement pivot receiving portion 217 and the movement support receivingportion 218 in the circumferential direction.

The aligning claw 211 includes an aligning surface 211 a which makescontact with the central opening portion of the disk (shown in FIGS. 3 aand 3 b) so as to align the disk, and a guiding inclined surface 211 bwhich guides the disk to the aligning surface 211 a. The guidinginclined surface 211 b includes a portion thereof which is arrangedaxially below the guiding portion 213. That is a portion radially inwardof the cylindrical portion 212 of the guiding inclined surface 211 bmakes no contact with the disk. That is, a portion radially outward ofthe cylindrical portion 212 guides the disk to the aligning surface 211.

According to FIGS. 4 a to 4 d, the claw member 220 includes the clawportion 221 and the pair of movement support portions 222 arranged oncircumferentially both sides of the claw portion 221. The movementsupport portion 222 supports the axial movement of the claw member 220.

The claw portion 221 includes the disk guiding surface 221 a which makesan initial contact with the disk when the disk is set on the chuckingmechanism 200, a tip portion 221 b which is formed continuously towardthe axially lower direction from the disk guiding surface 221 a andradially outwardly, and a disk retaining surface 221 c which is formedcontinuously toward the axially lower direction from the tip portion 221b and retains the disk.

The disk guiding surface 221 a guides the disk to the disk retainingsurface 221 c. Also, the disk guiding surface 221 a is a plane surfacehaving no inclination. The disk retaining surface 221 c includes aninclined surface which is inclined such that the further radiallyoutward a portion thereof is the axially upper the portion is, and whichmakes contact with an upper end of the central opening portion of thedisk when the disk is set on the disk setting surface 101 b. Here, thedisk guiding surface 221 a is arranged axially above a bottom surface ofthe top plate portion 215 before the disk is set on the chuckingmechanism 200. Since the disk guiding surface 221 a is a plane surfacehaving no inclination, an axial length of the claw portion 221 isminimized. Consequently, the chucking mechanism 200 can be designedhaving a reduced axial thickness.

Also, mirror polishing which allows the disk to travel smoothly to thedisk retaining surface 221 c is applied on the disk guiding surface 221a and the disk retaining surface 221 c. By virtue of such configuration,the disk can be attached to and detached from the chucking mechanism200.

According to FIG. 4 d, the claw portion 221 includes at the innercircumferential surface a protrusion 221 d protruding radially inwardlyso as to make contact with the elastic member 230. The protrusion 221 dincludes at an upper portion thereof a protrusion inclined surface 221 d1 which is inclined such that the further radially inward a portionthereof is the axially lower the portion is. Also, the claw portion 221includes at a radially inner surface and a bottom portion thereof aninner circumferential surface side inclined surface 221 d 2 which isinclined such that the further radially outward a portion thereof is theaxially lower the portion is.

The pair of movement support portions 222 attached to the claw portion221 are extending radially inwardly from a radially innercircumferential side of the claw portion 221. Also, the movement supportportion 222 includes the movement pivot portion 222 a which is a pivotalportion of the movement of the claw member 220, and the movement assistportion 222 b which is arranged radially inward of the movement pivotportion 222 a and guides the claw member 220 in the radial direction.Also, the movement support portion 222 includes at a surface thereofwhich is connected to the upper side contact surface 222 a 2 and whichis inclined such that the further radially a portion thereof is theaxially lower the portion is. By virtue of such inclined surface, whenthe tip portion 221 b of the claw member 220 moves axially downwardly,the movement support portion 222 makes no contact with the top plateportion 215.

The movement pivot portion 222 a preferably includes a movement pivotside curved surface 222 a 1 which slides with a top surface of themovement pivot receiving portion 217. The movement pivot side curvedsurface 222 a 1 needs at least enough curve to allow the tip portion 221b to move in the axial direction. In particular, the movement pivot sidecurved surface 222 a 1 of the movement pivot portion 222 a haspreferably an even curvature radius. By virtue of such configuration,only the tip portion 221 b of the claw member 220 is allowed to move inthe axial direction.

Also, the movement pivot portion 222 a preferably includes at a portionextending radially inwardly from a bottom end surface of the movementpivot side curved surface 222 a 1 an extending plane surface 222 c. Theextending plane surface 222 c is a plane surface which is substantiallyparallel with the top surface of the movement pivot receiving portion217 when the claw member 220 is contained within the center case 210.

Also, the pair of movement support portions 222 are arrangedsubstantially on circumferential sides of the claw member 220 preferablyincluding the pair of movement assist portions 222 b. Also, a surface ofthe movement assist portion 222 b opposed to the movement supportreceiving portion 218 preferably includes a movement support portionside curved surface 222 b 1 which protrudes toward the movement supportreceiving portion 218. The movement support portion side curved surface222 b 1 is a curved surface which allows the claw member 220 to slidewith the upper movement support surface 218 a and the lower movementsupport surface 218 b.

A configuration of the chucking mechanism 200 prior to when the disk(not shown in FIG. 5) is set thereon will be described with reference toFIG. 1 and FIG. 5. FIG. 5 is a cross sectional view of the chuckingmechanism 200 before the disk makes contact therewith.

According to FIG. 5, the claw portion 221 protrudes radially outwardlyfrom the opening 216 of the center case 210. Also, the elastic member230 is compressed and contained within the center case 210. The elasticmember 230 is arranged between an outer circumferential surface of thebase portion 214 and an inner circumferential surface of the clawportion 221. Also, the elastic member 230 makes contact with theprotrusion 221 d arranged at the inner circumferential surface of theclaw portion 221. The compressed elastic member 230 provides a radialforce to the claw portion 221 in the radially outward direction.

Next, according to FIG. 5, the movement pivot portion 222 a of themovement support portion 222 makes contact with the innercircumferential surface of the cylindrical portion 212 so as to preventthe claw member 220 from moving excessively in the radially outwarddirection. Also, the movement pivot portion 222 a makes contact with thetop surface of the movement pivot receiving portion 217.

The movement pivot portion 222 a preferably includes at the top surfacethereof the upper side contact surface 222 a 2 operable to make contactwith the bottom surface of the top plate portion 215. Prior to when thedisk makes contact with the chucking mechanism 200, the upper sidecontact surface 222 a 2 is substantially opposed to the bottom surfaceof the top plate portion 215 via a minute gap in the axial direction.That is, since the upper side contact surface 222 a 2 is not in contactwith the bottom surface of the top plate portion 215 prior to when thedisk is set on the chucking mechanism 200, an area in which the clawmember 220 and the center case 210 make contact with one another will bereduced. Also, when the tip portion 221 b moves in the axially downwarddirection, the upper side contact surface 222 a 2 is not in contact withthe top plate portion 215, the area in which the claw member 220 and thecenter case 210 make contact with one another will be reduced allowingthe claw member 220 to move in the radially inward direction smoothly.By virtue of such configuration, the disk will be set on the chuckingmechanism 200 smoothly.

Also, the movement assist portion 222 b is arranged above the lidportion 101 via an axial gap. That is, an axial position of the clawmember 220 is determined by the movement pivot portion 222 a and the topsurface of the movement pivot receiving portion 217. If the axialposition of the claw member 220 is determined by the contact between thelid portion 101 and the movement assist portion 222 b, an assembly errorof the rotor holder 100 and the center case 210 will affect the axialposition of the claw member 220. According to the present invention,however, the axial position of the claw member 220 is determined by themovement pivot portion 222 a and the top surface of the movement pivotreceiving portion 217, and therefore, is less likely to be affected bythe assembly error. Therefore, the chucking mechanism 200 according tothe present preferred embodiment of the present invention offers areliable quality. Also note that the movement assist portion 222 b issubstantially opposed to the lower movement support surface 218 b of themovement support receiving portion 218 via a minute gap.

It is to be noted that there is no extra component between the bottomsurface of the disk retaining surface 221 c and the top surface of thelid portion 101. That is, the side opening portion 216 a extends to abottom end portion of the cylindrical portion 212, and therefore, aspace S1 which defines an axial space between the bottom surface of thedisk retaining surface 221 c and the top surface of the lid portion 101is minimized while the claw portion 221 makes no contact with the topsurface of the lid portion 101 when the claw portion 221 is at thelowest position in the axial direction. According to the presentinvention, the excessive movement of the claw member 220 in the axialdirection is prevented by the movement pivot portion 222 a and themovement pivot receiving portion 217, and therefore, it becomes possibleto design the space S1 having a minimum space and a preferable accuracy.By virtue of such configuration, it becomes possible to design thechucking mechanism 200 having a preferable thinness.

According to FIG. 1, it is preferable that the base portion 214 of thecenter case 210 is arranged to reach in the axial direction a centralportion in the axial direction of the elastic member 230, or morepreferably below in the axial direction of the elastic member 230. Byvirtue of such configuration, the center case 210 is operable to containand affix to the rotor portion (e.g., rotor holder 100, rotor magnet 110and shaft 90) the claw member 220 and the elastic member 230. Therefore,the chucking mechanism 200 will be assembled with facility and aproductivity of the brushless motor will be improved.

Movement of Claw Member

Hereinafter, movement of the claw member 220 when a disk D is set on thechucking mechanism 200 will be described with reference to FIG. 6through FIG. 11. FIG. 6 is a cross sectional view of the chuckingmechanism 200 when the disk D begins to make contact with the diskguiding surface 221 a. FIG. 7 is a cross sectional view of the chuckingmechanism 200 according to the present invention in which the movementassist portion 222 b is arranged at a position of a curved surface 218c. FIG. 8 is a cross sectional view of the chucking mechanism 200according to the present invention in which the movement assist portion222 b slides over the upper movement support surface 218 a. FIG. 9 is aschematic cross sectional view of the chucking mechanism 200 accordingto the present invention in which the tip portion 221 b thereof is atthe axially lowest position. FIG. 10 is a schematic cross sectional viewof the chucking mechanism 200 according to the present invention inwhich the claw member 220 retains the disk D. FIG. 11 is a crosssectional view of the chucking mechanism 200 according to the presentinvention in which an inner configuration of the claw portion 221according to FIG. 9 is shown. Hereinafter, the disk D is a multi-layereddisk including an upper disk Da and a lower disk Db wherein the disk Dais pasted to the disk Db via an adhesive. Note that the elastic member230 is omitted from FIGS. 6 through 10 in order to better show arelationship between the claw member 220 and the center case 210.

According to FIG. 6, a central opening portion D1 of the disk D makescontact with the disk guiding surface 221 a. Then, the tip portion 221 bof the claw member 220 moves in the axially downward direction. Themovement of the claw member 220 is supported via a movable support pointRC which is a point at which the movement pivot portion 222 a makescontact with the movement pivot receiving portion 217. Here, a movingradius R1 of the claw member 220 in the axially downward directionequals a distance between the movable support point RC and the tipportion 221 b, and therefore, when the movable support point RC isarranged far from the tip portion 221 b, the moving radius R1 can beincreased. Consequently, a rotational force applied to the claw member220 in the axially downward direction is reduced, which also reduces theforce required to set the disk D on the chucking mechanism 200. That is,the chucking mechanism 200 allows the disk D to be set thereon smoothly.

The movement assist portion 222 b moves axially upward when the tipportion 221 b moves axially downward. Also, when the movement assistportion 222 b moves upward in the axial direction slightly, the movementassist portion 222 b makes contact with and slides on the lower movementsupport surface 218 b. At this point, the claw member 220 moves radiallyinwardly along the lower movement support surface 21 b. Also, when thetip portion 221 b of the claw member 220 moves in the axially downwarddirection, the axial gap between the movement support portion 222 andthe lid portion 101 is gradually increased.

Next, according to FIG. 7, the movement assist portion 222 b moves tothe position of the curved surface 218 c. At this point, the movementassist portion 222 b makes contact with both the lower movement supportsurface 218 b and the upper movement support surface 218 a. At theposition of the curved surface 218 c, the claw member 220 begins to movesubstantially in the radial direction. Here, since the tip portion 221 bis already moving in the axially downward direction, the claw member 220is allowed to move in the radial direction while an angle defined by thetop surface of the disk guiding surface 221 a and the central axis J1remains large. Therefore, when the disk D is being set on the chuckingmechanism 200, a great amount of force pushing the claw member 220 inthe axially downward direction will not be required.

Next, according to FIG. 8, when the disk D moves further downward in theaxial direction, the movement assist portion 222 b makes contact withthe upper movement support surface 218 a since the claw member 220 movesradially inwardly. The force applied to the disk D to set the disk D onthe chucking mechanism 200 is, because of the inclined surface of theupper movement support surface 218 a, shifted to the radially inwarddirection. Also, the tip portion 221 b moves axially in the downwarddirection along the inclination of the upper movement support surface218 a.

The movement pivot portion 222 a moves radially inward by sliding on thesurface of the movement pivot receiving portion 217. Here, since the topsurface of the movement pivot receiving portion 217 is arrangedperpendicularly to the central axis J1, the claw member 220 will not beforced to move axially downwardly due to the force to set the disk Donthe chucking mechanism 200. The claw member 220 is allowed to moveradially inwardly.

Next, according to FIG. 9, when the claw member 220 is at the radiallyinnermost point (i.e., when the tip portion 221 b makes contact with theinner circumferential surface of the central opening portion D1 of thedisk D), the tip portion 221 b is at the axially lowest point. The pointat which the tip portion 221 b is determined by the way in which themovement assist portion 222 b and the upper movement support surface 218a make contact with one another. Also, when the tip portion 221 b is atthe lowest point in the axial direction as shown in FIG. 9, an axialheight (L1) of the tip portion 221 b from the disk setting surface 101 bis greater than an axial height (L2) which is an axial length betweenthe disk setting surface 101 b having set thereon the disk D and a line(BL) bordering the disk Da and the disk Db. Since the L1 is axiallyabove the BL from the disk setting surface 101 b, a chucking failure inwhich the tip portion 221 b interferes with the BL.

The movement pivot portion 222 a slides over the top surface of themovement pivot receiving portion 217. Note that the top surface of themovement pivot receiving portion 217 extends radially inwardly furtherthan an innermost point to which the movement pivot portion 222 areaches. Therefore, an entire sequence of radial movement of the clawmember 220 will be conducted over the movement pivot portion 222 a andthe movement pivot receiving portion 217. Since the claw member 220 isallowed to move substantially only in the radial direction, the elasticmember 230 will not be deformed which may happen when the claw member220 moves in the axial direction. By virtue of such configuration, thedisk D will be set on the chucking mechanism 200 smoothly.

Also, when the tip portion 221 b is at the axially lowest point as shownin FIG. 9, the protrusion inclined surface 221 d 1 which is arranged atthe upper portion of the protrusion 221 d and is a mechanism to preventthe elastic member 230 from being deformed in the axial directionbecomes substantially perpendicular to the central axis J1 (see FIG.11). The inner circumferential surface side inclined surface 221 d 2which is arranged at the radially inner surface and the bottom portionof the claw portion 221 becomes substantially parallel to the centralaxis J1. By this, when the claw member 220 is at the axially lowestpoint, the protrusion inclined surface 221 d 1 is operable tosubstantially prevent the protrusion 221 d from interfering with theelastic member 230. Also, when the claw member 220 is at the axiallylowest point, the inner circumferential surface side inclined surface221 d 2 is operable to prevent the elastic member 230 from moving upwardin the axial direction, substantially preventing deformation thereof.Consequently, the elastic member 230 is allowed to provide the radialforce to the claw portion 221 without being interfered by the top plateportion 215.

In is to be noted that when the protrusion inclined surface 221 d 1 isas shown in FIG. 9, the protrusion inclined surface 221 d 1 is notlimited to being substantially perpendicular to the central axis J1. Theprotrusion inclined surface 221 d 1 can be designed such that thefurther radially inward a portion thereof is the axially lower theportion is when the tip portion 221 b is at the axially lowest point asshown in FIG. 9.

Next, according to FIG. 10, the tip portion 221 b slides along the innercircumferential surface of the central opening portion D1 of the disk Din the axial upward direction and reaches the top end of the centralopening portion D1. Then the disk D is retained by the claw member 220.

Also, while the disk D is retained by the claw member 220, the extendingplane surface 222 c makes contact with the top surface of the movementpivot receiving portion 217. A point (hereinafter, referred to as asupport point NC) at which the extending plane surface 222 c makescontact with the top surface of the movement pivot receiving portion 217will function as a fulcrum via which the claw member 220 moves in theaxially upward direction. Then, at a contact point TC, the upper sidecontact surface 222 a 2 of the movement support portion 222 makescontact with the bottom surface of the top plate portion 215. At thecontact point TC, the claw member 220 is prevented from movingexcessively upward in the axial direction when the disk D is removedfrom the chucking mechanism 200. By virtue of such configuration, anangle defined by the disk retaining surface 221 c and a surfaceperpendicular to the central axis J1 will be kept at an optimal degreeso as to securely retain the disk D. Also, since the extending planesurface 222 c and the movement pivot receiving portion 222 a makecontact with one another, and the upper side contact surface 222 a 2 andthe bottom surface of the top plate portion 215 make contact with oneanother, the tip portion 221 b of the claw member 220 is substantiallyprevented from moving in the axially upward direction, while the axialmovement of the claw member 220 is executed within an axial spacebetween the movement pivot receiving portion 217 and the top plateportion 215. By virtue of such configuration, the movement of the clawmember 220 will be controlled within an allowable error of assemblingthe center case 210, and therefore, a reliable chucking mechanism willbe provided.

Also, the movement pivot receiving portion 217 includes a plane surfaceextending radially inwardly. Also, the extending plane surface 222 c ofthe claw member 220 is substantially parallel with the movement pivotreceiving portion 217, and therefore, substantially prevents the tipportion 221 b of the claw member 220 from moving in the axially upwarddirection when the claw member 220 moves radially inwardly.

Axial Distance between Tip Portion and Disk Setting Surface

Hereinafter, an axial distance between the tip portion 221 b of the clawportion 221 and the disk setting surface 101 b will be described withreference to FIG. 12. FIG. 12 is a graph indicating a correlationbetween a rate of occurrence of chucking failure and axial height(hereafter, referred to as L1 shown in FIG. 9) of the tip portion 221 bmeasured from the disk setting surface 101 b when, for example, a DualDisc which includes a CD and a DVD pasted to one another via adhesive isplaced on the disk setting surface 101 b with the CD side of the dualdisc on the bottom. Note that the adhesive is not applied to an entiresurface connecting the CD and the DVD. Also note that the vertical axis(Y) of the graph indicates the frequency (%) of the occurrence of themalfunction of the chucking mechanism 200 and the horizontal axis (X)indicates the value (mm) of L1.

According to FIG. 12, the greater the value of L1 is, the smaller thefrequency of the occurrence of the malfunction of the chucking mechanism200 becomes. When such relationship is numerically denoted, it isapproximately: Y=−614.64X+667.63. That is, when Y is 0, no malfunctionof the chucking mechanism occurs (i.e., when X equals approximately1.08). Therefore, the value of L1 at which Y becomes 0 is the preferablevalue for L1. It is to be appreciated that the value X may change inaccordance with the amount of adhesive used in the Dual Disc.

Hereafter, an axially downward movement of the claw member 4 whensetting a disk 6 on a conventional chucking mechanism 1 will bedescribed with reference to FIGS. 15 and 16. FIG. 15 is a crosssectional view of the conventional chucking mechanism 1 when the clawmember 4 makes contact with a central opening portion 6 a of the disk 6.FIG. 16 is a cross sectional view of the conventional chucking mechanism1 in which the tip portion 4 b thereof is at an axially lowest position.Note that the disk 6 is a multi-layered disk including an upper diskbase 6 b and a lower disk base 6 c pasted to one another.

According to FIG. 15, the tip portion 4 b of the claw member 4 movesaxially downwardly when the claw member 4 makes, at a top surfacethereof, contact with a bottom end of the central opening portion 6 a,then the claw member 4 moves radially inwardly.

However, according to the conventional chucking mechanism 1, the axialposition of the claw member 4 is lowered when the disk 6 makes contacttherewith and the claw member 4 is at a radially innermost positioninside a center case 3 (see FIGS. 15 and 16). That is, the tip portion 4b is also moved axially downward causing the tip portion 4 b to besubstantially at a line bordering between two disk bases 6 b and 6 c. Bythis, the chucking failure in which the tip portion 4 b gets struckbetween the two disk bases 6 b and 6 c may occur.

Also, since the disk retaining surface 4 a includes an upward guidingsurface 3 d is arranged at a portion corresponding to a lower sidesurface thereof, the claw member 4 needs to be arranged axially abovethe upward guiding surface 3 d. Therefore, such configuration made itdifficult to design a thin chucking mechanism 1. Also, the radiallyinward movement and the axially downward movement of the tip portion 4 bare conducted via the sliding movement of the lower side surface of thedisk retaining surface 4 a and the upward guiding surface 3 d, andtherefore, the claw member 4 was extended in the axial direction. Bysuch configuration, it became difficult to design the claw member havinga preferable axial thickness while achieving a preferable movement ofthe claw member 4 in the axially downward direction and in the radiallyinward direction.

On the other hand, the chucking mechanism 200 according to the presentinvention, since the movement pivot receiving portion 217 is a planesurface which is substantially perpendicular to the central axis J1, thetip portion 221 b of the claw member 220 moves in the axially downwarddirection and in the radially inward direction preventing the entireportion of the claw member 220 from moving in the axially downwarddirection. Therefore, the chucking mechanism 200 according to thepresent invention minimizes the occurrence of the chucking failure.

Also, the movement of the tip portion 221 b is determined by themovement pivot receiving portion 217 and the movement support receivingportion 218. Here, since the movement pivot receiving portion 217 is aplane surface perpendicular to the central axis J1, the axial positionof the tip portion 221 b with respect to the disk setting surface 101 bwill be determined with facility. By virtue of such configuration, aconfiguration of the movement support receiving portion 218 will besimplified, and the chucking failure will be substantially prevented.Also, since the movement pivot receiving portion 222 a is arranged onthe side of the claw portion 221, and the movement assist portion 222 bis arranged radially inwardly of the claw portion 221, the movementpivot receiving portion 222 a and the movement assist portion 222 b aredesigned with greater degree of freedom. Also, since the movement pivotreceiving portion 217 and the movement support receiving portion 218 aredesigned with greater degree of freedom, the claw member 220 can bedesigned to have a preferable thickness while achieving a preferablemovement of the tip portion 221 b of the claw member 4 in the axiallydownward direction and in the radially inward direction.

Disk Driving Apparatus

Hereinafter, a disk driving apparatus according to a preferredembodiment of the present invention will be described with reference toFIG. 13. FIG. 13 is a cross sectional view seen in the axial directionof the disk driving apparatus according to the present preferredembodiment of the present invention.

According to FIG. 13, a disk driving apparatus 300 preferably includes abrushless motor 320 which fits an opening 311 arranged at a center of adisk shaped disk 310 and rotates the disk 310 in a concentric manner, anoptical unit 330 which emits an optical light at the disk 310 in orderto store data on the disk 310 and to reproduce data from the disk 310, agear mechanism 340 which moves the optical unit 330 in the radialdirection with respect to the 310, and a housing 350 for accommodatingtherein the brushless motor 320, the optical unit 330 and the gearmechanism 340.

The gear mechanism 340 includes a motor 341, and a torque receiving gear342 which receives a rotary torque generated by the motor 341.

The housing 350 preferably includes a bordering plate 351 preferablymade of a thin plate so as to divide the disk 310 and the gear mechanism340. Also the housing 350 preferably includes an opening 352 throughwhich the disk 310 will be inserted and rejected.

The optical unit 330 preferably includes a storing/reproducing portion331 which emits an optical light, and a moving portion 332 which isarranged vertically with respect to the moves the storing/reproducingportion 331. The moving portion 332 preferably includes an engagingportion 332 a which engages with the torque receiving gear 342. Thestoring/reproducing portion 331 is engages with the moving portion 332and is thereby allowed to move in the radial direction.

The torque receiving gear 342 rotates due to the engagement with a gearportion 341 a which is attached to the motor 341. The moving portion 332moves in the radial direction due to the engagement of the torquereceiving gear 342 with the engaging portion 332 a. Then, due to themoves of the moving portion 332, the storing/reproducing portion 331moves in the radial direction.

Since the disk driving apparatus 300 includes the brushless motor 320according to the present invention, the disk driving apparatus 300 isallowed to be thin while the disk 310 is set thereon smoothly, andretained thereby securely.

While the present invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

For example, although the present preferred embodiment assumes that themovement support receiving portion 218 includes the upper movementsupport surface 218 a and the lower movement support surface 218 b, thepresent invention is not limited thereto; the movement support receivingportion 218 may only include the upper movement support surface 218 a.When the movement support receiving portion 218 only includes the uppermovement support surface 218 a, the upper movement support surface 218 ais preferably configured such as to allow the movement assist portion222 b to make a stable contact therewith.

For example, although the present preferred embodiment assumes that thedisk D is a multi-layered disk, the present invention is compatible witha single layered disk.

For example, although the present preferred embodiment assumes that theprotrusion 221 d of the claw member 220 includes the protrusion inclinedsurface 221 d 1 in order to minimize the deformation occurring to theelastic member 230, the present invention is not limited thereto; a stepportion 221 d 3 may be arranged at a radially inner surface of theprotrusion 221 d, via a radial gap therebetween, which may be includedat the surface of the elastic member 230 making contact with the elasticmember 230 in order to minimize the deformation of the elastic member230 in the axial direction. As shown in FIG. 17, due to the gap betweenthe elastic member 230 and the step portion 221 d 3, even when the clawmember 220 moves in the axially downward direction, the deformation inthe axially upward direction occurring to the elastic member 230 due tothe protrusion 221 d will be minimized.

For example, the elastic member 230 of the present invention may makecontact with the base portion 214 of the center case 210, or the elasticmember 230 may make contact with the base portion 214 and also with theleveled portion 101 a.

For example, although the present preferred embodiment of the presentinvention assumes that the opening 216 includes the widened portion 216b 1, the present invention is not limited thereto. A through hole may bearranged penetrating between the top surface and the bottom surface ofthe top plate portion 215 which is circumferentially apart from theopening 216. In such case, the movement pivot receiving portion 217 isarranged at a position corresponding to the through hole. Acircumferential width of the through hole is equal to or greater thanthat of the movement pivot receiving portion 217.

1. A chucking mechanism operable to detachably set thereon a discoiddisk including a central opening portion, the chucking mechanismcomprising: a center case arranged concentrically with a predeterminedcentral axis, including a cylindrical portion which fits the centralopening portion, a top plate covering an axially upper side of thecylindrical portion, and a plurality of openings arranged in acircumferential direction extending from the cylindrical portion to thetop plate portion; a claw member movable with respect to the opening,protruding in a radially outward direction from the cylindrical portion,and making contact with the central opening portion of the disk; anelastic member providing radial force to the claw member; and a turntable including a disk setting surface setting thereon the disk, whereinthe claw member includes a claw portion having a disk retaining surfacemaking contact with the central opening portion and retaining the disk,and a movement support portion having a movement pivot portion which isarranged on circumferential side of the claw portion and is a pivotalportion for a movement of a tip portion in, at least, axially downwarddirection, and a movement assist portion which is arranged radiallyinwardly of the movement pivot portion and guides the claw member movingin the radially inward direction, the center case includes a movementpivot receiving portion receiving movement of the movement pivotportion, and a movement support receiving portion receiving movement ofthe movement assist portion, and the movement support receiving portionand the movement pivot receiving portion each are arranged radiallyinwardly of the cylindrical portion, wherein the center case is made byan injection molding and made of a resin material, the center caseincludes at least two movement pivot receiving portions arrangedcorrespondingly to the openings circumferentially apart from oneanother, wherein the opening includes a widened portion whosecircumferential width is greater than a rest of the opening, wherein thecircumferential width of the widened portion is greater than acircumferential width of a pair of movement pivot receiving portions,and wherein the circumferential width of the widened portion is greaterthan a radial width of the movement pivot receiving portion.
 2. Thechucking mechanism according to claim 1, wherein the top plate portionaxially opposed to the movement pivot receiving portion includes athrough hole whose width is greater than a circumferential and radialwidth of the movement pivot receiving portion.
 3. The chucking mechanismaccording to claim 2, wherein the top plate includes a plurality of thethrough holes arranged apart from one another in the circumferentialdirection, and a portion of a bottom surface of the top plate portionmakes contact with a top surface of the movement pivot portion when thetip portion moves in the axially upward direction.
 4. The chuckingmechanism according to claim 1, wherein the claw member includes at bothcircumferential sides thereof a movement pivot portion, and thecircumferential width of the widened portion is smaller than acircumferential width of the claw member including the movement pivotportions.
 5. The chucking mechanism according to claim 1, wherein themovement support portion makes contact with an inner circumferentialsurface of the cylindrical portion when the disk is not set on thechucking mechanism.
 6. The chucking mechanism according to claim 5,wherein a portion of the movement support portion making contact withthe inner circumferential surface of the cylindrical portion is themovement pivot portion, and the movement pivot portion has at a portionthereof between the inner circumferential surface of the cylindricalportion and a top surface of the movement pivot receiving portion aneven curvature radius.
 7. The chucking mechanism according to claim 6,wherein the top surface movement pivot receiving portion and the innercircumferential surface of the cylindrical portion is connected to oneanother via a curved surface, and a curvature radius of the curvedsurface is smaller than the curvature radius of the curved surface ofthe movement pivot receiving portion.
 8. The chucking mechanismaccording to claim 1, wherein the movement pivot receiving portionincludes a plane surface substantially perpendicular to the centralaxis.
 9. The chucking mechanism according to claim 1, wherein theopening includes a side opening portion arranged toward the cylindricalportion, and an upper side opening portion arranged upwardly from theside opening portion, and the side opening portion penetrates to abottom surface of the cylindrical portion.
 10. A brushless motorincluding the chucking mechanism according to claim 1, the motorcomprising: a rotor portion having therein a rotor magnet rotatingconcentrically with the central axis, and a stator portion havingtherein a stator arranged opposite from the rotor magnet rotatablysupporting the rotor portion.
 11. A disk driving apparatus including thebrushless motor according to claim 10, the apparatus comprising: anoptical unit optically storing data on the disk and reproducing data onthe disk, and a gear mechanism moving the optical unit in the radialdirection.